Transformer



June 25, 1929. E. A. KUEN .7

I TRANSFORMER Filed March so, 1926 2 Sheets-Sheet l [NVEN OR r A ofintv June 25, 192 9. E. A. KUEN 1 1.718.826

TRANSFORMER Filed March so, 1925 2 Sheets-SheL 2 (NVEMQR Patented June 25, 1929.

UNITED STATES TRANSFORMER.

Application filed. March 30, 1926. Serial N'o. 98,427.

This invention relates to a transformer especially designed for use in radio frequency a-n'lplification stages of radio apparatus. It is a well known fact that one or more stages of tuned radio frequency amplification will in general oscillate unless some measures are taken to prevent oscillation. There are three methods at present in common use to prevent oscillation. One of these consists in a system ofreversed capacity feed back as in the neutrodync type of receiver. Another consists in a reversed inductive feed back as in the well known Roberts or superdyne types .of receivers.

The third consists in a scheme of absorption, as in circuits employing potentiometers or series plate resistances, as well as in circuits employing transformers which are purposely mounted so that a part of the field therefrom is passed through relatively large masses of metal, as-for example condenser plates and frames. In this last instance the induced currents in the metal parts of the condenser operate to absorb suflicient energy to damp out all oscillations. Ordinarily this scheme is objectionable because too much of the energy of the transformer is thus absorbed, thereby detracting greatly from the efficiency of the circuit, but, nevertheless, it is principally upon this latter method of oscillation prevention that I have chosen to improve by the development of the transformer which will now be described.

In the drawings I have illustrated two embodiments of my invention, one being shown in Figs. 1 to4 inclusive and the other in Figs. 5 to 8 inclusive.

An object of my invention is to produce a transformer which is novel in that it is possessed of an induced field which, because of the character of the design is composed .of two divisions, namely, an external portion and an internal portion.

A further object is to produce a transformer in which the winding may be arranged to produce an induced field which is composed of two parts, each of which is proportioned in accordance with the value of the field strength necessary to obtain complete elimination of all oscillation through absorption, as previously explained.

These and other transformer described in the following specification and illustrated in the acco npanying drawings in which;

PATENT- oFFicE.

EUGENE A. KUEN, OF CINCINNATI, O I-IIO;

the transformer shown in Fig. 5

objects are attained in the Fig. 1 is a perspective view of the transformer embodying one form of my invention. I

Fig. 2 is a perspective view of the framework skeleton upon which the winding is placed, one complete frame encompassing convolution having been shown in place to illustrate the method of winding.

Fig. 3 is a somewhat diagrammatic view showing the manner of winding, perhaps to better advantage than the showing made in Fig. 2. Fig. 4 is a sectional view showing the construction of the transformer as taken on line 4 -t of Fig. 1, also illustrating diagrammatically one of the field components produced by the transformer shown in Fig. 1 as well as Fig. 5.

Fig. 5 is a perspective view of the transformer embodying another form of my invention.

Fig. 6 is a perspective view of the framework skeleton upon which the winding of the transformer shown in Fig. 5 is placed, the method of winding being illustrated by showing one complete frame encompassing convolution in place.

Fig. '7 is a somewhat diagrammatic view showing'the manner of winding the transformer shown inFig. 5, perhaps more clearly thanas shown in Fig. 6.

Fig. 8 is a sectional view showing the construction of the transformer as taken on line 88 of Fig. 5, also illustrating diagrammati- Cally one of the field components produced by as well as Fig. 1. i

I will describe first the transformer shown in Figs.- 1 to 4: inclusive. This transformer, in common with that shown in Figs. 5 to 8 inclusive, employs a framework having the same construction. Thefollowing description as, to' this framework applies to both Figs. 2 and 6 and the same reference numerals will be used in each. f Such a framework preferably consists of'two annular members 11 and 12 which are separated by a series of spacers 13 to 18 in elusive. I have found it convenient to provide six of these spacers forthe proper strength of the frame, but such a number of spacers need not be adhered to strictly. v

In the winding of the coils upon the spool orframe I may start at any convenient point as for example at 19 on one annular member 11. 1 he pa e Wire d g n y ver t m mber 12 and then diagonally down the outside face of member 12, through the center of the spool, across diagonally to member 11 and diagonally up the outer face of member 11 to a point 20. The winding is then continued in a similar manner to a point 21 which corresponds to points 19 and 20, after which continued winding brings it back topoint 19. This method is then continued repeatedly, each time placing one layer of wire to the side of and against the previously wound layer un til the required amount of Wire has been placed upon the spool. It will be seen that I have described the winding of the transform 'er in a manner such that three complete convolutions of the wire are made progressively around the spool before the starting point is again reached ready for another spool encircling winding operation. This is but a convenient disposition oflthe convolutions of the windings, it being quite possible to place as many convolutions upon the spool as may be desired in order to complete one entire spool encircling operation. Thus upon the completion of each spool encircling winding another is started and placed close to and in contact with the preceding wrapping until successive windings produce a coil of sufficient proportions. Let us assume that such a coil constitutes the secondary 22 of .the transformer. It is then necessary to start and proceed with the winding of the primary 23 in the same manner as has been described for the secondary 22. It may be mentioned that the terminals of the primary may be brought out on one side of the spool and the terminals of the secondary on the other side of the spool this arrangement being for convenience in the disposition of the binding posts. For example, in the finishing of the transformer I provide two side plates 24 and 25 of dielectric material which are held upon the windings of the spool with a bolt 26. In one of these plates the binding posts 27 and28 of the secondary are mounted, and in the other the binding posts 29 and 30 of the primary are mounted. A prop or support 31 may be held in place by the bolt 26 so that the transformer may be conveniently mounted. A

The form of the invention shown in Figs. to 8 inclusive, embodiesthe well known style of duolateral orhoney comb winding.

The method of winding this consists in providing one plate 12 of the spool with an aperture 32 adjacent to its edge and then in passing the wire through this aperture until one half of its length lies on each side of the aperture. One complete spool encircling winding of the desired number of convolutions is then made with one branch of the wire in one direction around the spool, followed by one complete spool encircling winding of the desired number of convolutions with the other branch of the wire in the opposite direction, this method being continued in alilGl'lliltlOD until the desired number of wrappings have been placed on the spool. As an alternative the wire constituting the one half on one side of the aperture may be all wound on the spool at one time and then followed by the winding of the remaining half of the spool in the opposite direction. The effect produced is the latticed or honeycom ed effect shown in the secondary 33 of Fig. 5. After both ends of the winding have been brought out on the same side of the spool, the winding of the primary coil 3% is started. If the number of wrappings is small, the attainment of a duolateral or latticed effect may be impossible, but such a coil may be wound with the adjacent convolutions in spaced relation to conform to the general distribution of the windings of the secondary, as shown in Fig. 5. This transformer, as with the one shown in Figs. 1 to 4-, may also be provided with si'de'plates 24 and upon which binding posts 27 to inclusive are mounted, with the bolt 26 and bracket 31.

The peculiar effect which attained-in both types of winding is the apparent disliing or dipping of the windings as disclosed in the sectional. view shown in Fig. 4. This is accentuated or decreased in accordance with the pitch which the convolutions take in being wound upon the spool, the reason being that each stretch of' wire between the spool ends or sides is of course straight while the periphery of these sides is curved, thus operating as each successive convolution is placed in position, to support the ends of these straight stretches of wire while theirmiddle points naturally lying lower than the highest pointo f the curved portions subtended by the straight portions of wire, will, when viewed across or transversely of the transformcr, produce the dips shown. Actually the dip decreases and would finally disappear completely if the pitch of the winding were changed to gradually approach a right angle to the sides of the spool.

Let us now discuss the feature of novelty in this invention. In the introductory re- ,marks I have made the statement-that the transformer produces a field which comprises two components. One of these components is a field possessing internal characteristics while the other component is a field possess ing external characteristics. By the term internal I refer to a field which in swirling fashion travels within the space between the upper and under layers of wire and 36, indicated by the faintly drawn lines and air rows 37 in Fig. 8, while by the term external I refer to the field which swirls around the outside of the transformer coils in the form of a doughnut as shown at 38 in Fig. 4. If the pitch of the coil winding be increased the characteristics of the coil will more nearly approach that of the cylindrical Winding so These characteristics are reversed as the pitch of the coil windings is decreased so as to cause the coil to present more of a toroidal appearance. To bring out the electrical distinctions of the two distinct types of coils to which I have just referred, it would be best perhaps to refer to the fields induced in each. The cylindrical winding produces a field such as I have attempted to illustrate at 38 in Fig. 4:, which lies wholly outside the windings or convolutions. The toroidal winding produces a field 37, as shown in Fig. 8, which lies wholly within the annular space enclosed by the convolutions of the coil. I have discovered that by employing these well known ch aracteristics of cylindrical and toroidal coils in a single structure certain very useful and desirable results may be accomplished. For example, the external field may be varied as to amount by winding the transformer with a pitched winding designed to produce just the necessary amount of external field to be at sorbed as described in the third method set forth in the second )ara ra )h on ia 'e 2 of this specification. This oscillation may be controlled without more energy loss than is absolutely necessary to damp such an oscillation tendency. It is therefore quite obvious that the most desirable field to control is the external field. This, as has been set forth, is increased by increasing the pitch of the winding so that it approaches more nearly to a cylindrical winding, decrease of the field being obtained by decreasing the pitch of the winding so that it approaches more nearly to a toroidal type of winding.

Having thus described my invention what I claim is:

A transformer consisting of a skeleton frame comprising substantially annular'end members spaced apart, a coil of wire wound thereon in a series of win-dings, each of said windings consisting of a series of convolutions of Wire encircling the frame by passing it across the outer face of the frame from end member to the other at an angle to the axis and plane of the frame, inwardly across the end face of one member of the frame, the interior of the frame from the opening of one member to the opening in the other member at a reverse angle to that first taken by the wire, outwardly across the end face of the other member, thence across the outer face of the frame from member to member at an angle substantially the same as that first taken by the wire and thence in rep-etition of the convolutions and angles of direction to complete the winding, each winding lying adjacent to the preceding winding, each member having end face width sufficient to effect separation of the outer and inner laps of wire of the convolutions, whereby a substantially annular space is enclosed by the coil windings, and a second coil wound upon the frame similarly to the first mentioned coil and in such relation therewith as to have induced therein a current responsive to the passage of a current through the'first mentioned coil.

In testimony whereof I have hereunto affixed my signature.

EUGENE A. KUEN.

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